Late to the party, but I'm mostly playing on Warmane's servers. Currently switching between Icecrown for the population and quicker levelling, and Icecrown which is much harder and slower with 1x rates.
I started on WoW Hardcore for the permadeath, and Kronos for the full Vanilla experience, but they're much less populated so they don't "feel" as much like MMOs, but rather RPGs where you can talk to and join others if you organise to meet up... which is fine of course, and I enjoy them, but I'm preferring the MMO experience right now.
My guess is legally protecting themselves against potential new laws and regulations, so they have more time to make changes or continue making money if these practices get outlawed.
It's not; it exists in computer and console gaming too, just to a lesser extent. As to why, my guess here is that mobile has a lower barrier to entry, and they're always accessible where a computer or console might not be. There's probably some sort of "cultural" aspect here too, where it's already prevalent in mobile so people are more accepting of it, but computer/console gamers had their own culture where this didn't exist for many decades and so won't be as accepting.